The present invention relates to a method of introducing ecologically harmful solid or sludge-like waste as well as mixtures of solid, sludge-like or liquid waste with binding agents into subterranean cavities filled with water or brine.
The storage of ecologically harmful waste in above-ground depots is becoming increasingly more difficult and is also problematic. Reasons for this are the decreasing availability of depots suitable for this purpose, the occurrence of precipitations, the expensive protection for avoiding ground water contamination as well as the problems of long-term integrity both of the conditioned waste and also of the above-ground depots themselves.
An alternative is to introduce waste into subterranean chambers of suitable geological formations.
As shown in tests for the final disposal of radioactive waste in underground facilities such as salt domes, a sufficient long term safety can be expected. These underground chambers can be filled with solid waste or also with suitable sludges. Another possibility is to introduce solid, sludge-like or even liquid waste after mixing it with a suitable binding agent such as cement, fly ash from coal fired power plants or gypsum. A solidification of these mixtures can then take place underground. Subterranean cavities can be produced in salt domes either by mechanically removing the salt or by dissolving salt with water. Cavities of this type are used for storing items such as petroleum.
However, cavities filled with water or brine in salt formations or in other typical geological formations are not suitable for the introduction of water-soluble wastes or not-yet-hardened mixtures of waste and binding agent. The noxious substances that can be present in such waste can pass into the water or brine and must be removed again. It has been found that mixtures with binding agents cannot achieve the required mechanical properties under water.